Table 2.

Plating efficiencies of nullD and intermediary/nullD strains, previously isolated G61A utilizer strains, and previously isolated G61D resistant strains in cells expressing exogenous D genes with the D34G mutation in cis with G61D and G61A mutationsb

StrainPlating efficiency (assay titer/permissive titer)a with indicated exogenous D gene
NoneWTG61DD34G/G61DG61AD34G/G61A
nullD10−41.0<10−4<10−4<10−4<10−4
intermediary/nullD<10−31.0<10−3<10−3<10−3<10−3
ut3d(F)S426L/nullD10−41.0<10−5<10−51.010−3
ut3d(B)H109Y/nullD<10−51.0<10−4<10−41.0<10−2
mh3dr(B)P102L1.00.50.5<10−41.010−3
mh3dr(B)P102L/(F)R233H1.01.01.00.41.00.6
  • a Permissive titers were determined in cells expressing the wild-type D gene.

  • b The intermediary/nullD strain contains all of the resistance mutations found in the intermediary strain and two amber mutations in the D gene. The utilizer strains, i.e., the ut3d(F)S426L/nullD and ut3d(B)H109Y/nullD strains, are capable of producing infectious virions when complemented by the G61A mutant external scaffolding proteins (11). The resistant mh3dr(B)P102L and mh3dr(B)P102L/(F)R233H strains are described in the text.